The earth's population has increased from about three billion in 1960 to about 6.2 billion in 2002, and is expected to increase to a peak of about 11 billion in around 2050 before slowly decreasing, i.e., in just 90 years the population of the world will have almost quadrupled. The population explosion has represented, and still represents, a major challenge as regards both increasing the access to clean drinking water for direct consumption and food production and meeting the ever more rapidly growing need for more food.
To date, the problem of the increasing need for food has been solved by a change-over from traditional agriculture to modern knowledge-based agriculture with extensive use of mechanical working power and scientifically based knowledge of how to cultivate land with maximum efficiency. Important factors are the use of artificial irrigation, synthetic fertilisers, chemical weed and pest control, and new gene-modified plants which give greater yields and are more resistant to pests. One example of the significance of modern agriculture is that in 1940 the USA produced 56 million tonnes of maize on 31 million hectares whilst in 1999 it produced 240 million tonnes of maize on 29 million hectares, i.e., a quadrupling of yield per area unit of cultivated land. In 1998 the world's food production was 5,034 million tonnes (source: FAOSTAT, 1999), of which 99% comes from agriculture whilst fishing and hunting accounts for 1%. Had this amount of food been evenly distributed, it would have been possible to give 900 million people more than today's population a healthy diet of 2,350 kcal per day. There is just sufficient food in the world today, and the increase in food production has taken place without any appreciable increase in the total cultivated area since 1960. But the battle is far from won. The world population is expected to double yet again during the next 50 years, which means that we must manage to almost double today's agricultural productivity if we are to avoid extensive famine in the world.
However, there are problems associated with modern agriculture. One serious problem that may be a major obstacle to obtaining the necessary doubling of production capacity is that access to fresh water is in the process of becoming scarce in large parts of the world. According to the World Meteorological Organization, 70% of the world's freshwater uptake in 1997 was used for irrigation of agricultural areas. And this amount of water was used by just 17% of the world's agricultural areas, which alone account for 40% of the total food production this year. In 1997 the United Nations estimated that one third of the world population lives in areas with a moderate to high stress level on the water supply, and it is expected that as much as two thirds of the world population may experience the same in 2025. This problem is aggravated in that today water is often used inappropriately as it is supplied to agricultural areas without any form of control of runoff and evaporation factors. Some studies have shown that plants in dry, hot areas make use of as little as 2% of the water that is supplied to the soil.
It is therefore obvious that optimal use of freshwater resources will be a very important factor in achieving productivity goals in tomorrow's agriculture, and that we need a method and means which can radically increase the level of utilisation of water supplied to agricultural areas.